Cancer is the leading cause of death in most industrialized nations, and the direct cause of cancer death is often its metastasis to the vital organs. Colorectal cancer is the third most common cause of cancer mortality in Japan. Every year, ˜100 new patients of colorectal cancer are diagnosed per population of 100,000, and the mortality rate is 30-40 per 100,000 patients; and it is still increasing.
Cancer treatment, such as chemotherapy and radiation has associated risks, and it is important to optimally select patients most likely to benefit. Although there are several studies on prognostic markers for colorectal cancer (Non-patent literatures 1-7), they are not enough to identify patients with good prognoses for whom risky therapy would not be necessary.